Abstract
Making choices about whether and when to engage cognitive effort are a common feature of everyday experience, with important consequences for academic, career, and health outcomes. Yet, despite their hypothesized importance, very little is understood about the underlying mechanisms that support this form of human cost-benefit decision-making. To investigate these mechanisms, we used the Cognitive Effort Discounting Paradigm (Cog-ED) during fMRI scanning to precisely quantify the neural encoding of varying cognitive effort demands relative to reward outcomes, within two distinct cognitive domains (working memory, speech comprehension). The findings provide strong evidence that the dorsal anterior cingulate cortex (dACC) plays a central and selective role in this decision-making process. Trial-by-trial modulations in dACC activation tracked the relative subjective value of the low-effort, low-reward option, with the strongest activity occurring when this was of greater value than the high-effort, high-reward option. In contrast, dACC activity was not modulated by decision difficulty, though such effects were found in other frontoparietal regions. Critically, dACC activity was also strongly correlated across the two decision-making task domains, and further predicted subsequent choice behavior in both. Together, the results suggest that dACC activity modulation reflects a domain-general valuation comparison mechanism, which acts to bias participants away from decisions to engage in cognitive effort, when the perceived subjective costs of such engagement outweigh the reward-related benefits. These findings complement work in other cost domains and species by pointing to a clear role of dACC in representing subjective value differences between choice options during cost-benefit decision-making.
Significance Statement Despite the growing popularity of decision-making paradigms to study the neural mechanisms underlying choices to engage in cognitive effort, there is still little consensus about how such decisions are implemented in the human brain. This study used two distinct versions of a cognitive effort decision-making paradigm during fMRI scanning to identify generalized brain mechanisms engaged while participants decided whether to engage in cognitive effort. Importantly, the results provide additional evidence that the dorsal anterior cingulate cortex is a key locus of cognitive effort-based decision-making. Specifically, this brain region signals the difference in relative value across choice options, making it an attractive target for future studies aimed at investigating the altered decision-making observed in populations for which apathy is commonly observed.
Footnotes
The research was supported by the National Institutes Health (R21-AG067295 to T.S.B. and subaward R24-AG054355 to J.L.C.). J.L.C. was additionally supported by T32-AG000030, T32-NS115672, and T32-NS007292. We would like to thank Alison Tay for their assistance with data collection. We also thank members of the Cognitive Control and Psychopathology Lab for helpful advice and discussions during manuscript preparation.
Rachel Brough is now affiliated with the Department of Psychology at the University of Denver. Jonathan Peelle is now affiliated with the Departments of Communication Sciences and Disorders and Psychology at Northeastern University.
The authors declare no conflicts of interest.
